#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
int fib(int n)
{
    if(n<=2)
	{
	    return 1;
	}
	else
	{
	    return fib(n-1) + fib(n-2);
	}
}
int main()
{
	int n = 0;
	int ret = 0;
	scanf("%d",&n);
	ret = fib(n);
	printf("%d\n",ret);
	return 0;
}

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